To my knowledge, this has never happened to me but I can understand your frustration if I am honest. There is nothing worse than having someone take something you wrote that is your own knowledge or own opinion and having them just copy and paste it as their own. I myself no matter where I post or write, I always ensure it's my own opinions, own knowledge, and own thoughts, and could never dream of taking someone else's work and passing it off as my own. If I ever do take anything it's usually for a quote and I make it a quote and link it back to the original author.